Patent GB-595263-A (GB)
Title: Improvements in or relating to electrical apparatus for producing a movement proportional to or a function of the value of the difference between two quantities
IPC: G06G7/14
Filed: 1944-12-13
Abstract: 595,263. Electric clocks. POWELL, H. M. Dec. 13, 1944, No. 25063. [Class 139] [Also in Group XL] Electrical apparatus for producing a movement proportional to or a function of the value of the difference between the quantities comprises means for rotating a soft iron di-polar armature at a speed proportional to or a function of the value of the one quantity, the armature being mounted on and frictionally coupled with a shaft of the driving means, means for producing a series of electrical impulses at a frequency which is proportional to or a function of the value of the other quantity, and an electromagnet having its pole-pieces arranged so that the armature rotates in the gap between them, the impulses being applied to the winding of the electromagnet to cause the armature to be advanced or retarded angularly in relation to the shaft of the driving means by an amount proportional to or a function of the value of the difference between the two quantities. In the embodiment shown in Fig. 1 the invention is applied to a device for "correcting" periodically a synchronous motor electric clock. A soft iron di-polar armature 1 is mounted frictionally on a spindle 2 rotated by a synchronous motor 3, through suitable gearing, at a speed proportional to the frequency of the alternating current supplied to the motor say one revolution per second. A master clock, not shown, supplies impulses at the rate of one per second to the winding 5 of an electromagnet the pole pieces 6 of which lie adjacent the poles la of the armature 1. The armature 1 rotates between the pole pieces 6 and its initial setting is such that the diametrical plane about which it is symmetrical bisects the arcuate faces 6a of the pole pieces 6. The impulses received by the electromagnet 5 are transferred via the pole pieces 6 to the armature 1 which is thus pulled forward or back into its initial setting every second depending on whether it is slow or fast in relation to the impulses. The motion of the armature may be transferred to an indicating pointer through a train of gears. In the embodiment shown in Fig. 4, the spindle 2 is screw threaded and the armature 1 has a central boss of two parts 1c, 1d each internally screw threaded. The periodic angular "correcting" movements of the armature 1 cause the armature to move axially along the spindle 2 and the pole pieces 6 in this case are extended parallel to the spindle 2 an amount corresponding to the range of axial travel of the armature 1. As shown a rod 13 carrying a pointer or an inking pen co-operates with the armature 1 to give an indication or a record of its position and so an indication or a record of the difference between the synchronous clock "time" and the master clock "time." The correcting movement of the armature may be transferred to the cage of a differential mechanism. The angular movement of the armature relative to its spindle may be used to control relay circuits or to operate gear for correcting the difference causing such relative movement.